The present invention relates to a speed transmission apparatus arranged between a drive engine and a drivable receiving device, for example a machine to be driven, industrial or agricultural, or the wheels of a motor car.
At the present time this transmission takes place by means of a gearbox provided with a defined number of ratios. The drawback of this type of transmission is its discontinuity. It can take place only by successive jumps.
In order to attempt to remedy this problem, there have already been provided, in the case of engines of low or medium power, transmission devices, known as continuous variators, which can however not be used for high powers, greater than approximately 40 continental HP (29.420 W).
For engines with higher powers, the use of automatic gearboxes has been provided for, which make it possible to avoid manual actions for changing transmission ratios, but the aforementioned discontinuity remains.